DETECTION OF NITROGEN CONTAINING AND NITROGEN FREE EXPLOSIVES
First Claim
1. A system for screening for the presence of explosives, the system comprising:
- a. collection means for collecting explosive residues;
b. loading means for loading said collected residues into a desorber;
c. pyrolysis means for pyrolysing said explosive residue to generate a gaseous sample;
d. first pumping means for pumping the gaseous sample sequentially into a luminol reaction cell followed by a very sensitive metal oxide sensor (MOS) array or partially into a luminol cell and a very sensitive metal oxide sensor (MOS) array;
e. said luminol producing chemiluminescence by a chemical reaction between said luminol and said gaseous sample within said reaction cell;
f. measuring means comprising photomultiplier tube or photodiode array for measuring the intensity of chemiluminescence and for outputting a first electrical signal indicative of the amount of explosive detected;
g. second pumping means for pumping a reduced quantity of said gaseous sample to said metal oxide sensor array, to prevent saturation of metal oxide detector;
h. resistance measuring means, for measuring resistance of oxide film on the metal oxide sensor, said resistance being changed by adsorption of said pumped gaseous sample;
i. said resistance measurement indicating the presence of said explosive;
whereby the chemiluminescence measurement is refined by the metal oxide sensor measurement to eliminate the interference composition from detection.
2 Assignments
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Accused Products
Abstract
A compact explosive detecting system collects explosive residues in the form of vapor powder. The residues are accumulated on a desorber which is subjected to pyrolysis to release a gaseous sample. The sample is pumped to a detecting system through a metering valve. A luminol cell reacts with the gaseous sample to create chemiluminescence, the light output of which is measured by a photo multiplier tube. The light intensity is indicative of the amount of explosive present. Based on the amount of explosive present, a metering valve is adjusted to pass the gaseous sample into a highly sensitive metal oxide sensor array to detect NO2 from nitrogen containing explosive and CO/CO2 from non nitrogen containing explosive. The metal oxide sensor array reliably selects explosives from those compounds indicating chemiluminescence.
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Citations
11 Claims
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1. A system for screening for the presence of explosives, the system comprising:
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a. collection means for collecting explosive residues; b. loading means for loading said collected residues into a desorber; c. pyrolysis means for pyrolysing said explosive residue to generate a gaseous sample; d. first pumping means for pumping the gaseous sample sequentially into a luminol reaction cell followed by a very sensitive metal oxide sensor (MOS) array or partially into a luminol cell and a very sensitive metal oxide sensor (MOS) array; e. said luminol producing chemiluminescence by a chemical reaction between said luminol and said gaseous sample within said reaction cell; f. measuring means comprising photomultiplier tube or photodiode array for measuring the intensity of chemiluminescence and for outputting a first electrical signal indicative of the amount of explosive detected; g. second pumping means for pumping a reduced quantity of said gaseous sample to said metal oxide sensor array, to prevent saturation of metal oxide detector; h. resistance measuring means, for measuring resistance of oxide film on the metal oxide sensor, said resistance being changed by adsorption of said pumped gaseous sample; i. said resistance measurement indicating the presence of said explosive; whereby the chemiluminescence measurement is refined by the metal oxide sensor measurement to eliminate the interference composition from detection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for screening for the presence of explosives, the system comprising:
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a. collection means for collecting explosive residues; b. loading means for loading said collected residues into a desorber; c. pyrolysis means for pyrolysing said explosive residue to generate a gaseous sample; d. pumping means for pumping the gaseous sample to a very sensitive metal oxide sensor (MOS) array; e. metering means for reducing the quantity of said gaseous sample to said metal oxide sensor array, to prevent saturation of metal oxide detector; f. resistance measuring means, for measuring resistance of oxide film on the metal oxide sensor, said resistance being changed by adsorption of said pumped gaseous sample; g. said resistance measurement indicating the presence of said explosive.
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Specification